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<html lang="en">

<head>
  <meta charset="UTF-8">
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  <title>Document</title>
</head>

<body>
  <script>
    class SuperArray extends Array {
      shuffle () {
        for (let i = 0; i <= this.length - 1; i++) {
          const j = Math.floor(Math.random() * (i + 1));
          [this[i],this[j]] = [this[j],this[i]]
        }
        return this
      }
    }
    let superArray = new SuperArray(1, 2, 3, 4, 5, 6, 7)
   console.log(superArray.shuffle())
  </script>
</body>

</html>
